The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
In computer networks such as the Internet, packets of data are sent from a source to a destination via a network of links (communication paths such as telephone or optical lines) and nodes (often routers directing the packet along one or more of a plurality of links connected to it) according to one of various routing protocols. One such type of protocol is a link state routing protocol. A link state routing protocol requires each router to maintain the entire map of the network. When a network link changes state from active to inactive (“goes up” or “comes down”) or the converse, a notification, often termed a link state advertisement (LSA) in Open Shortest Path First (OSPF) or link state packet (LSP) in Intermediate System-to-Intermediate System (IS-IS), is flooded throughout the network. All the routers that receive the message record the change and recompute their routes accordingly. Interior gateway protocols (IGPs) such as OSPF and IS-IS are examples of link state protocols.
In some link state routing protocols, Router Capabilities LSAs/LSPs are designed to carry application-specific information not related to IGP routes or topology. These LSAs/LSPs are flooded to all the nodes. However, some of the nodes in the system do not need the information contained in the Router Capabilities (RC) LSA/LSP. Sending the RC LSAs/LSPs to every node unnecessarily loads both the network and any node that does not need the information.
Such “unnecessary” messages include periodic RC LSA/LSP Refreshes which occur, for example, every thirty minutes for OSPF and every fifteen minutes for ISIS. A problem with flooding periodic LSA/LSP Refreshes is that the RC LSA/LSP Refreshes may not contain any new information and therefore, are unnecessarily burdening both the network and receiving nodes.
Even when new information is contained in an RC LSA/LSP the message is flooded to nodes that are not interested in the information. For example, when a tunnel endpoint floods the RC LSAs/LSPs carrying the tunnel endpoint information, the RC LSA/LSP is sent to all the nodes in the network, even though only those nodes that participate in the tunnel or are in the topology path of another tunnel endpoint may need to receive, or be interested in, the information.
Based on the foregoing, there is clearly a need for an approach to reduce the number of unnecessary messages sent by nodes.